Subnet Calculator

How To Use

To use: Input IP Address in
dotted-decimal format (e.g. 10.0.0.1). Classful calculation is
based on classful network addressing architecture. Classful networking
was used until the introduction of CIDR
(classless inter domain routing). Calculations are given instantly when
typing. Invalid input gives no results. Calculator will assume that
unfinished IP addresses end with zeros. Network class will be determined automatically. Only Network
classes A,B and C will calculate results. For classes network
calculations, please use CIDR calculator, for route aggregation, please use Supernet calculator.

Class

First octet range

Leading bits

Number of subnets

Number of hosts

Class A

1-126

0

128 (27)

16777216 (224)

Class B

128-191

10

16384 (214)

65536 (216)

Class C

192-223

110

2097152 (221)

256 (28)

Select Mask in dotted-decimal format or by adjusting network bits or max sub-networks you want.

Address

Internet Protocol Address (or IP) are used by network devices as host
identifiers for communication with other network devices using Internet
Protocol. Internet Protocol version 4 (IPv4) are 32-bit binary numbers,
usually represented in human-readable dotted-decimal format (e.g.
78.84.160.206). Certain IP addresses are reserved by the Internet
Assigned Numbers Authority (IANA) for special use and cannot be used as
host addresses (listed in RFC 5735). To convert IP address value between
binary, decimal and hex, please use IP conversion.

Mask

The MASK is binary number (also usually represented in
dotted-decimal format) used to separate network and host parts in IP
address. IPv4 subnet mask is 32 bits large. In a valid subnet mask
network part is represented with "1" from left side followed and ended
by host part "0" - 11111111.11111111.11111111.00000000 (binary form),
255.255.255.0 (dotted-decimal form) or simply "/24" (where 24 represents
that subnet network part is 24 bits long). Subnet calculator allows
calculation for 255.255.255.254.

Host Bits

Subnet bits are the number of bits used to identify subnet. IP
network is divided into network prefix and host identifier. Host bits
are there to identify hosts and it is divided into subnet and host
identifier.

Subnet mask

IP address

Network

Hosts

IP address

Network

Subnet

Hosts

Max Networks and Hosts

Maximum number of subnets and hosts available in the specified subnet mask.

Max Subnets = 2subnet_bits

Max Hosts = 2host_bits - 2 (subtraction of network
and broadcast addresses. Exceptions are subnets with /31 subnet mask
where there is no subtraction part)

Network ID

This is the Reserved Address that represents the Network. It is
destination part of the IP routes and it cannot be assigned to host as
an identifier. Network ID is calculated by using bitwise AND between IP
address and subnet mask.